116 BULLETIN OF THE 



Othonia aculeata Stm. 

 ITyas aculeata Gibbes, Proc. Am. Assoc. Adv. Sci., 1850, p. 171. 

 Othonia aculeata Stimpson, Notes on N. American Crust., p. 3. 

 Othonia Lherminieri Desbonne et Schramm, Crust, de la Guadeloupe, p. 20. 

 The specimens in the collection are all young, and occurred as fol- 

 lows : — 



At Key West, 2 to 5 fathoms. 



At the Tortugas, 5 to 6 fathoms. 



Off the Tortugas, January 29, 1868, in 13 fathoms. 



Subfamily MITHRACINAE. 



Mithrax hispidus H. M.-Edw. 



Cancer hispidus JIerbst, Naturg. d. Krabben u. Kiebse, pi. xviii, fig. 100. 



Maia spinicincta Lamarck, Anim. sans Vert., V, 241. 



Mithrax spinicinctus Desjiarest, Consid. sur les Crust., p. 150; pi. xxiii, 



figs. 1,2. 

 Mdhrax hispidus H. Milne-Edwards, Hist. Nat. des Crust., I, 322. Gibbes, 



Proc. Am. Assoc. Adv. Sci., 1850, p. 172. Stimpson, Notes on N. 



American Crust., p. 60. Smitu, Trans. Connecticut Acad, of Arts and 



Sciences, II, 2, 32. 

 This well-known species occurred at Key West, in from 2 to 5 fathoms. 



Mithrax pleuracanthus nov. sp. 



This is closely allied to M. hispidus, but is a smaller species, with a 

 somewhat narrower carapax. The protuberances of the carapax, and the 

 teeth or spines of the orbits and the basal joint of the antennae, are 

 sharper and more prominent, and there are small tubercles on the intes- 

 tinal, branchial, and hepatic regions, which do not occur in M. hispidus. 

 The minute punctures of the surface are less apparent than in that 

 species. 



Tbe dimensions of a male specimen are : Length of the carapax, 0.57 ; 

 breadth, 0.55 inch; proportion of length to breadth, 1 : 0.9G5. 



This species can scarcely be the M. affinis of Desbonne and Schramm 

 (Crust de la Guadeloupe, p. 10), the description of which applies to it in 

 most respects, for those authors state that the front, rostrum, and orbits 

 are like those of Mithraculus scidptus. 



It occurred at Key West in from 2 to 5 fathoms, and at the Tortugas in 

 5 to C fathoms. There is in the Smithsonian Collection a specimen taken 

 at St. Thomas by A. H. Riise, Esq. 



Mithrax acuticornis nov. sp. 

 Carapax much longer than broad, and tuberculated, sparsely on the 

 gastric region but more closely posteriorly and at the sides, the tubercles 



